Resin Glycosides from the Roots of Operculina macrocarpa (Brazilian Jalap) with Purgative Activity

Abstract

Analysis of the methanol-soluble resin glycosides from the roots of Operculina macrocarpa was assessed by generating NMR profiles of five glycosidic acids obtained through saponification, acetylation, and recycling HPLC purification. Operculinic acid H (1), two novel hexasaccharides, operculinic acids I (2) and J (3), the known purgic acid A (4), and a quinovopyranoside of (−)-(7R)-hydroxydecanoic acid, operculinic acid K (5), were isolated. Three intact resin glycosides related to 1, the novel macrocarposidic acids A (6) and B (7), in addition to the previously known macrocarposidic acid C (8), were also purified with isovaleroyl, tigloyl, and exogonoyl [(3S,9R)-3,6:6,9-diepoxydecanoyl] groups as esterifying residues. A selective intramolecular lactonization was produced to generate a macrocyclic artifact (17) during acetylation of 1, resembling the distinctive structure of the Convolvulaceous resin glycosides.

Computational metabolomics illuminates the lineage-specific diversification of resin glycoside acylsugars in the morning glory (Convolvulaceae) family

“…This pattern is corroborated by studies in C. hederacea and C. soldanella containing 2S-methylbutyric acid as the C5 acyl chain (Ono et al, 2021;Takigawa et al, 2011). As per prediction here, the two studies in Operculina also demonstrate a dominance of C5 (2S-methylbutyric) and tiglic acids in two Operculina species (Ding et al, 2012;Lira-Ricárdez et al, 2019). Generally, short chain fatty acids were more represented in RG structures than long chain saturated and unsaturated fatty acids.…”

“…In contrast, the two Operculina species and Xenostegia tridentata had hexose instead of deoxyhexose or pentose as their most preferred sugar for adding the hydroxyacyl chain. Eight previously published structures from O. macrocarpa and O. turpethum (Ding et al, 2012;Lira-Ricárdez et al, 2019) with the hydroxyacyl chain bonded to glucose agree with this finding. Based on these observations, we infer that hydroxyacyl chain addition (or at least the glycosidic bond formation) with deoxyhexoses was likely the ancestral state for RG biosynthesis, with lineage-specific shifts to hexose or pentose.…”

Glycosidic Acid Content from the Roots of Operculina hamiltonii (Brazilian Jalap) and Some of Their Phytopharmaceuticals with Purgative Activity

“…GC-MS analysis of the lipophilic fraction allowed the identification of isobutyric, 2-methylbutyric, cinnamic, n-hexanoic, n-octanoic, n-decanoic, n-dodecanoic and n-hexadecanoic acids. Exogonic acid, a chemical marker for the resin of O. macrocarpa (Lawson et al 1992;Lira-Ricárdez et al 2019), was not detected. Acid hydrolysis of the saponification product provided three monosaccharides, identified as l-rhamnose, d-fucose and d-glucose.…”

“…For example, turpethic acids A-C (7-9), pentasaccharides having a monohydroxylated 12S-hydroxy fatty acid as their aglycone with a C 15 (7), C 16 (8), or C 17 (9) chain, were isolated from the Indian Jalap (Ding et al 2012), O. turpethum S. Manso (Akbar 2020). From the roots of O. macrocarpa, operculinic acid H (10), a hexasaccharide of 3S,12S-dihydroxyhexadecanoic acid (Ono et al 2009), was isolated, in addition to operculinic acids I (11) and J (12), containing the same glycoside of 10 and diverging in their aglycones, 12S-hydroxyhexadecanoic and 11S-hydroxyhexadecanoic acids, respectively (Lira-Ricárdez et al 2019).…”

“…In continuation of our chemical studies on the Brazilian jalaps (Lira-Ricárdez et al 2019), operculinic acids L-N (13-15) were isolated as peracetylated glycosidic acids (19)(20)(21). Compound 19 is a tetrasaccharide with the same oligosaccharide core of operculinic acid C (3) with 12S-hydroxyheptadecanoic acid as the aglycone.…”